Collapsible bicycles have been proposed earlier in a large number of variations and with different folding principles. German Patent Specification 1.084.159 thus describes a collapsible bicycle, in which the two wheels, when the bicycle is in a collapsed condition, are situated close to each other, which folding method as proven itself to be the most space-saving.
A drawback with earlier known collapsible bicycles is that the bicycle has to be dismantled, whereby is obtained several separate parts, beside the fact that the folding requires use of special tools. The above-mentioned Patent Specification has tried to set aside this problem by displacing certain frame parts along frame posts and by unhooking other frame posts instead of unscrewing them, but this requires efficient clamping joints and necessitates several complex hand manipulates beside requiring rather strong power for tightening and releasing the clamp couplings. It is also known to fold the bicycle frame about one or mroe mainly vertical pivot axes, but the volume reduction obtained is indifferent and the collapsed bicycle is still bulky.
The collapsible bicycle has not become a success up until now, and the reason for this is the contradictory functional requirements, at one hand for stability and on the other hand for a simple manner of collapsing the bicycle. The latter requirement necessitates a plurality of joints, which, from stability aspects, always presents problems, particularly if they shall also be dismountable. Beside stabillity and simple collapsibility, the bicycle shall have low wiehgt, but it shall also be easy to handle, i.e. it shall be possible to handle as one unit, when collapsed. A plurality of loose or partially continuous, joint-less details will become difficult to handle and to transport and there is a big risk that one part or some parts are lost.